Auction formats in the art tend generally to be of the sealed-bid or ascending-bid variety. In the standard sealed-bid auction, bidders--in one single bidding round--simultaneously and independently submit bids to the auctioneer, who then determines the auction outcome. In the standard ascending-bid auction, bidders--in a dynamic bidding process--submit bids in real time until no more bids are forthcoming. An ascending-bid format offers the advantage that there is feedback between participants' bids: each bidder is able to infer other bidders' information about the value of the object(s) as the auction progresses and incorporate this information into his subsequent bids. This feedback tends to result in more efficient auction outcomes as well as more aggressive bidding, resulting in higher expected revenues for the seller. However, an ascending-bid format also has the disadvantage that--in complex environments--the auction may last for a long time, and require serious bidders to devote substantially all their time during this extended period of the auction. (For example, some of the ascending-bid auctions conducted by the Federal Communication Commission in 1994-96 have consisted of well over 100 bidding rounds and lasted upwards of three months each. In particular, the D-E-F block broadband PCS auction, which began on Aug. 26, 1996, was still in progress on Dec. 20, 1996, and had already conducted 229 bidding rounds.) In addition, the real-time aspect of the bidding--which gives the standard ascending-bid auction its desirable properties--also implies that any bidder's continued participation (and thus the auction's success) may be imperiled by communication breakdowns or other lapses anytime in the course of the auction. By contrast, while a sealed-bid format does not provide participants the opportunity to respond to their competitors' bids, the auction may be completed much more quickly and requires only a single bid submission by bidders, so participation is less onerous for bidders and may be less susceptible to communication breakdowns.